Close your eyes and imagine that you’re living in a futuristic city. Looking at the horizon, you can see towering wind turbines gently rotating in the wind. On the other side, you can see a whole field of solar panels. A nearby dam uses river water to produce even more electricity. The air you breathe is clean and fresh. The cars and other vehicles don’t give off any smoke or pollution. Your surroundings are clean and green, with plants growing all around you. Far away, you can see an old power plant, which is being demolished to make way for new, alternative energy sources. You can also see several large factories nearby, but none of them are emitting black smoke! This is what a city looks like where alternative energy rules the world .
So, what actually is alternative energy? As you may know, today we rely almost completely on petroleum and coal-based energy sources which are called fossil fuels. Energy companies obtain these resources from deep inside the earth’s surface and refine it to produce different fuels, like gas, gasoline, diesel and kerosene. These fuels are burned in power plants to produce electricity. Petroleum was formed by the remains of tiny plants and animals that died millions of years ago. Coal, on the other hand, was formed by larger plants like ferns. These dead materials were covered by layers of mud, rock, and soil over the years. Because of the pressure caused by all the top layers and the heat from earth’s core, the plant and animal remains transformed into petroleum and coal. Because it took millions of years for petroleum and coal to form, this means that the amount of fossil fuel resources in the world are limited and won’t last forever. Since the number of people in the world and businesses in the world keep increasing and advancing, the need for energy is also rising. This is why finding new ways to harness energy is so important! Luckily, the world already has a lot of alternative energy sources and smart scientists and engineers are always working on finding new ways to harness energy and improve the technology we already have.
The alternative sources of energy include solar power, wind power, hydro power, tidal energy, geothermal energy, and biomass energy. These are called renewable energy, because they are naturally replenished in a short amount of time unlike petroleum. For example, there’s always more sun and wind!
First let’s talk about solar energy. Solar energy is the energy we get from the sun. The sun is an incredibly huge, ball of energy which lights Earth with its rays we receive as sunlight. For thousands of years, people have used the sun’s energy to cook food, dry clothes, and keep warm. In our day, people have invented technologies to transform sunlight or solar energy into electrical power. This is done by solar cells, which are also called “photovoltaic” cells. “Photo” means “light” in Latin and “voltaic” stands for “electricity”. So, it’s basically turning sunlight into electricity! Pretty amazing, right? Solar panels are made by putting together many solar cells. If you’ve ever seen shiny panels on rooftops, those are solar panels. A few of my neighbors have them. In Arizona, solar panels are popular because we get LOTS of sunshine. It can also save people money, because the panels capture the light energy from the sun and turn it into electricity that can be used to power all the electric equipment in their house. Solar panels are sometimes used to power boats, food trucks, buildings, and satellites. Although solar energy IS renewable, how much energy they can produce depends on the time of day, season of the year and location in the world. For example, Arizona is much better for solar panels than a place like England that is often cloudy.
Now, let’s talk about wind energy. Wind energy is made from the wind, which is freely available to us just like sunlight. During the middle ages, people used wind power to pump water or grind grains. They built windmills to do that. Nowadays, people use a large structure called a wind turbine to make electricity using wind power. You may have seen these wind turbines as very tall structures that have long blades to capture the wind. Wind turbines can be around 400 feet tall, because the turbine blades need to reach high up into the atmosphere where the wind is faster than on the ground. The power of the wind is transformed into electricity by a small machine called a turbine generator which is connected to the turbine blades. Energy companies build hundreds of wind turbines in large fields where there are a lot of wind. These areas covered with wind turbines are called “wind farms”. When our family drives to California we pass through a huge wind farm. If you’ve never seen a wind farm look up pictures of San Gorgonio Pass. It’s pretty amazing.
The next form of alternative energy is hydropower or hydro energy and is made by using the power of moving water. In the past, people have used the power of water by making water wheels in rivers. Ancient Egyptians used hydro energy to grind grains and early Americans used it to saw wood. In the 1800’s, scientists discovered how to make electrical energy using hydro energy by turning the turbines of a generator. So, it works a little bit like wind power. To harness hydro energy today, people build a dam across a river which creates a water reservoir, which is like a man-made lake. By making a reservoir, we can have a controlled flow of water which can be used to generate electricity. That is, powerplant workers can control the amount and speed of the water flowing out of the dam. So, unlike solar or wind energy, hydro power is more constant and controllable. In Arizona we have the Hoover Dam and Glen Canyon Dam that generate a ton of electricity using hydro power. Be sure to lookup pictures of these impressive dams.
Tidal power is another type of hydro power. But instead of using inland waters like rivers and reservoirs, the energy of seawater is used to make electricity from tidal energy. Ocean tides usually occur twice daily, and tidal powerplants use turbine generators to convert that energy into electricity. Tidal turbines are placed in the path of the tidal waves. When the waves hit the turbine blades, they begin to spin. This movement is transformed into electric power using the turbine generators. So, you can see that the design of wind turbines and hydro turbines are very similar. However, tidal power can change based on the season. We cannot control it like how we control the power generated from a reservoir.
Geothermal energy is a form of alternative energy, that is obtained from the earth’s core. You may already know that the core of the earth is packed with heat. You can sometimes see this heat coming out of volcanoes and geysers. Geothermal energy can be used for heating, cooking and in electricity generation. We get it by circulating water or other liquids through underground tubes. The liquids absorb the geothermal heat and bring it back up. The captured heat can be directly used for heating. It can also be used to produce electricity using steam turbines.
Another really interesting form of alternative energy is biomass. Biomass is biological materials such as sugar cane, straw, wood chips and many other plant materials. These can be burned to generate electricity instead of burning fossil fuels. Biomass can also be used to make other types of fuel such as diesel and biogas that can replace petroleum-based fuels. This makes biomass different and more important than the other types of alternative energy we discussed. That’s because biomass can be used to produce solid, liquid and gaseous forms of energy instead of just electricity.
It’s pretty exciting to consider all of the new forms of energy that have been developed over the last 100 years and the improvements that are happening every day. Does alternative energy interest you? If so, do an internet search to watch videos of some of the amazing things people are doing to use renewable energy and what is being done at places like wind and solar farms. Also, more and more engineers and inventors are needed to solve the energy problems we have. Does engineering interest you? If so, math and science are important subjects to improve at. Also, being creative and coming up with lots of ideas. Can you think of an interesting way to use alternative energy to power something you use everyday?
With all of the new inventions, we have more and more options and not one of them is perfect, so many people believe a combination of technologies will solve the problems of pollution while sustaining all of our energy needs. There are over 7 billion people on this planet, so we need to find ways we can all live here and have enough energy without polluting this precious gift we can be given.